The invention starts out from a locking device for steering head mountings of two-wheel vehicles, such as bicycles, having an upper bearing unit and a lower bearing unit which rotationally connect a shaft tube of the fork of the two-wheel vehicle immovably with a steering head tube of the frame of the two-wheel vehicle.
In order to ensure a clearance-free mounting between the steering head tube, belonging to the frame of the two-wheel vehicle, and the shaft tube of the fork, an axial force must be applied permanently on the mountings of the latter. Because of the thread, which weakens the cross section of the shaft tube as well as because of damage to the shaft tube, the threaded connections, which are known for this purpose and for which the handle stem is pressed by means of a set screw, screwed into the shaft tube of the fork, against a divided compression ring of the upper bearing unit (U.S. Pat. No. 5,095,770) or for which a fastening nut, screwed onto the shaft tube, presses a clamping ring against a conical centering ring (U.S. Pat. No. 5,544,905), have a greater susceptibility for breaking prematurely in situations of extreme stress.
An independent locking of the steering head mounting, for which the handlebars can be dismantled without affecting the bearing clearance set, comprises a compression ring, the inner surface of which is provided with sharp, tooth-like grooves, by means of which it is pressed by means of compression elements against the outer casing of the shaft tube. These compression elements embrace the compression ring radially and may consist of a conical threaded connection or of a cylindrical clamping ring (U.S. Pat. No. 5,332,245). For this solution also, the shaft tube is affected by the application of radial clamping forces, since the sharp edges of the compression ring work their way into the surface of the shaft tube and these grooves can be the cause of premature breakage in the case of extreme stresses.
In a case of a similar solution, which evidently makes do without the mechanical impairment of the shaft tube, the compression ring is pressed by means of a threaded connection, consisting of a half bearing for the upper bearing unit and the lock nut, against the shaft tube. For this purpose, the compression ring has an upper short conical surface and a lower long conical surface, as well as several axial slots, which are open at the top. By screwing the half bearing and the lock nut together, the elastic regions of the compression ring, remaining between the slots, are pressed against the shaft tube (DE G 94 20 884.0). The disadvantage of this solution as well as of the aforementioned locking of the steering head mounting of U.S. Pat. No. 5,332,245 consists therein that the axial pressure for ensuring the absence of clearance in the bearing initially must be applied on the compression ring by hand, for example, by depressing the handle stem and, moreover, until the threaded connections or the clamping connections take effect. Such a manual application of pressure is physically strenuous and, moreover, not reproducible.
Finally, a steering head mounting for two-wheel vehicles is known, for which the compression ring is part of the inner ring of the upper bearing unit. The clamping ring can be placed on the conical outer surface of the compression ring. The conical outer surface of the compression ring, as well as the complementary inner surface of the clamping ring are configured so that the connection is self retaining after a single application of pressure on the clamping ring, so that spring-back of the elastic part of the inner ring is prevented permanently (DE 103 30 419 A1). If tapered roller bearings, which also absorb axial forces, are used in the steering head mounting, the self retention between the inner ring and the compression ring admittedly prevent a spring-back of the elastic parts of the inner ring during or after the installation. However, an additional locking device is required in order to absorb the axial components of the forces of the tapered roller bearing. It is also a disadvantageous that the tapered seat connection cannot be loosened readily.